Light-emitting diode (LED) is a semiconductor light-emitting device, taking semiconductor P—N junction as the light-emitting structure. Currently, gallium nitride (GaN) is regarded as the third-generation semiconductor material. However, due to large refractive index difference between the GaN material and air, light-emitting efficiency of the light-emitting diode is much restricted for a significant part of light, when emitted from the semiconductor layer to the air, is completely reflected back due to light-emitting angle and passes through the internal part of the semiconductor, which losses part of energy that finally transfers into heat, thus imposing heat dissipation burden for the light-emitting diode. Surface roughening, as a technology for improving light-emitting efficiency of the light-emitting diode, has complex process and high cost; existing roughening surface is concentrated over the chip grain surface; and the improved side roughening is not sufficient to improve light-emitting efficiency due to small light-emitting area at side.